Dynamically modeling fault step overs using various friction laws

Abstract

AbstractIt is well known that fault step overs can under some circumstances allow through‐going rupture and under other circumstances cause rupture to terminate. However, the effects of different friction law formulations on jumping rupture have not been extensively explored. In this study we use the 2‐D dynamic finite element method to investigate how different frictional parameterizations affect the ability of rupture to jump a step over, in both extensional and compressional settings. We compare linear slip‐weakening friction and three forms of rate‐ and state‐dependent friction: the aging law, slip law, and slip law with strong rate weakening. We have found that for friction parameterizations with the same effective slip‐weakening distance, the functional forms of such friction laws can have a significant effect on maximum jump distance. With friction laws scaled to have equivalent fracture energies, we find that the functional forms of such friction laws have a second‐order effect on jumping rupture. Finally, with our specific parameterizations we find that delays in rupture across the step over systems can lead to a previously unseen mode of supershear transition once the rupture renucleates on the secondary fault segment, even if the initial stress field precludes such a transition. Studies using multiple friction laws in complex geometries such as fault step overs can lead to better understanding of the dependence of rupture properties on the type of friction law utilized in models and statistical analysis.